There would be up to 100 deaths, thousands more walking wounded, and not one house would be safe if a 5.5 magnitude earthquake hit the centre of Brisbane, international researchers predict.
However, the scenario is entirely hypothetical and highly improbable, says Dr James Daniell from the Karlsruhe Institute of Technology in Germany, who has modelled the impact of an earthquake in the River City.
Dr Daniell and his colleague Dr Bijan Khazai have explored the consequences of a possible earthquake in Brisbane and intend to share their results with the city’s disaster management coordinators.
“We’re putting forward a ‘what if’ scenario for Brisbane,” Dr Daniell said.
No fault line has been identified directly below Brisbane, but Dr Daniell has investigated what could happen in the event a 5.5 magnitude earthquake occurred just seven kilometres below the CBD.
“It’s a theoretical earthquake, it’s something that may not happen ever,” he said.
But if it did, there would be widespread damage.
“Unlike floods, earthquakes cause a lot more damage over a wider area,” Dr Daniell said.
He said at least 100,000 houses across Brisbane would suffer cracking, structural failure or partial collapse.
“No house would really be protected from a high-intensity earthquake,” Dr Daniell said.
However, Dr Daniell said Brisbane’s traditional tin and timber homes would likely withstand the shaking better than those made of bricks and mortar.
“Bricks are more vulnerable,” he said.
City high-rises would largely be spared, but older, more vulnerable buildings would be significantly damaged.
The damage bill could easily climb to $20 billion, Dr Daniell said.
The 6.3 magnitude quake which struck the New Zealand city of Christchurch in 2011 killed 185 people and destroyed about 10,000 suburban homes. The damage bill in Christchurch topped $40 billion.
Brisbane is considered to have a lower earthquake risk, but the region has experienced earthquakes in the past.
The Emergency Management Australia disaster database shows a 4.4 magnitude quake hit Mount Glorious, 20 kilometres north-west of Brisbane, on November 17, 1960, causing some damage in the Lockyer Valley region.
And houses were damaged when a magnitude 4 earthquake struck near Gatton in 1988.
In Central Queensland, meanwhile, Seismology Research Group leader Mike Turnbull has previously raised concerns about a fault line just 30 kilometres west of Bundaberg - the origin of a quake at least 5.4 in magnitude in 1935.
Dr Daniell drew on one of the world’s largest databases of earthquakes and other hazards as part of the predictive modelling process for Brisbane.
He said he would like to carry out further in-depth analysis of the possible effects of an earthquake in southeast Queensland, including the potential impact on dams, infrastructure and significant buildings.
There have been more than 100 earthquakes in Australia over the past century, Dr Khazai said.
“Most are minor tremors, but the fact remains that a significant earthquake should be considered in disaster planning,” he said.
Geoscience Australia says Australia experiences about 200 earthquakes of magnitude 3.0 or more every year. It says on its website that a potentially disastrous earthquake of magnitude 6 or more occurs every five years in the country.
Thirteen people died when a 5.6 magnitude earthquake struck Newcastle, in New South Wales, on December 28, 1989.
The quake damaged more than 35,000 homes, leaving an estimated damage bill of $4 billion.